Dryer having gas heater

ABSTRACT

A dryer includes a nozzle communicated with a gas pipe for supplying gas; a gas injection passage which is provided in the nozzle and through which the gas is injected; and an air intake passage provided in the nozzle so as to be communicated with the gas injection passage, wherein a cross section of the gas injection passage is smaller than a cross section of the air intake passage.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to Korean patent application number 10-2007-0139506, filed on Dec. 27, 2007, which is incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

The present invention relates to a dryer, and more particularly, to a dryer having a gas heater which can prevent incomplete combustion.

FIG. 1 is a structural view showing a flow path of a conventional dryer and FIG. 2 is a partially broken perspective view of the conventional dryer.

Referring to FIGS. 1 and 2, the conventional dryer includes a cabinet 2 which forms an external appearance of the dryer and provided with an opening formed in front thereof and through which laundries to be dried are put into the dryer, a drum 12 which is rotatably mounted inside the cabinet 2 to accommodate the laundries to be dried and has opened front and rear portions for allowing air to pass therethrough, a heater 18 which is disposed inside the cabinet 2 to heat the air sucked into the cabinet 2, an intake duct 20 which guides the heated air passed through the heater 18 to the rear of the drum 12, an exhaust unit 22 which exhausts the air polluted by drying the laundries to the outside of the cabinet 2, a blower fan (not shown) which is installed in the exhaust unit 22, and a motor (not shown) and a belt 40 which drive the drum 12 and the blow fan to be rotated.

A lifter 11 is mounted on an inner peripheral surface of the drum 12 to lift up and drop the laundries to be dried. Also. the exhaust unit 22 includes a lint duct 25 which receives the air from the drum 12 to filter foreign substances from the air by a filter 24 mounted therein, a fan housing 26 which communicates with the lint duct 25 and houses the blower fan and an exhaust duct 27 which communicates with the fan housing 26 at one end thereof and extends to the outside of the cabinet 2 at the other end.

Operation of the conventional dryer having the above described structure will be described.

First, by operating the dryer after putting the laundries to be dried into the drum 12 and closing a door (not shown), the motor is driven to rotate the drum 12 and the blower fan and the heater 18 is operated together. At this time, as the drum 12 is rotated, the laundries to be dried in the drum 12 are lifted up and dropped by the lifter 11. External air is sucked in the heater 18 by a blowing force generated upon the rotation of the blower fan, heated to air with high temperature and low humidity and then discharged to the inside of the drum 12 through the intake duct 20. The air with high temperature and low humidity supplied to the inside of the drum 12 is brought into direct contact with the laundries to dry the laundries and changed to air with low temperature and high humidity. While drying the laundries, the air is moved toward the front of the drum 12 and then exhausted to the outside of the dryer through the exhaust duct 27.

In the conventional dryer, since a heater heated by electric energy is installed inside a pipe communicated with the intake duct, it takes much time to heat the heater and it is difficult to reduce the time and cost taken for the drying operation as the high price electric energy is used as a heat source. Therefore, it is required to improve the problems.

SUMMARY OF THE INVENTION

Embodiments of the present invention are directed to a dryer having a gas heater which can prevent incomplete combustion of gas.

Also, embodiments of the present invention are directed to a dryer having a gas heater which can use various kinds of the gas.

In one embodiment, a dryer includes a nozzle communicated with a gas pipe for supplying gas; a gas injection passage which is provided in the nozzle and through which the gas is injected; and an air intake passage provided in the nozzle so as to be communicated with the gas injection passage, wherein a cross section of the gas injection passage is smaller than a cross section of the air intake passage.

A diameter of the gas injection passage is smaller than a diameter of the air intake passage.

The dryer may further include a fastening part provided in the nozzle to mount the nozzle. The length of the fastening part is greater than the diameter of the air intake passage. The nozzle includes a nozzle for a first gas and a nozzle for a second gas. The nozzle for a first gas includes a nozzle for Liquefied Petroleum Gas (LPG) and the nozzle for a second gas includes a nozzle for Liquefied Natural Gas (LNG) and the diameter of the gas injection passage of the LPG nozzle is smaller than the diameter of the gas injection passage of the LNG nozzle. Also, the diameter of the air intake passage of the LPG nozzle is smaller than the diameter of the air intake passage of the LNG nozzle. In the LPG nozzle, the diameter of the gas injection passage is 1.2 to 1.6 mm and the diameter of the air intake passage is 1.8 to 2.2 mm. The length of the fastening part is 3.8 to 4.2 mm. Also, in the LNG nozzle, the diameter of the gas injection passage is 1.8 to 2.2 mm and the diameter of the air intake passage is 2.8 to 3.2 mm. The length of the fastening part is 3.8 to 4.2 mm.

Preferably, the nozzle has a shape of a polygonal prism and the air intake passage is formed on a face which forms the polygon.

The cross section of the gas injection passage is the smallest of cross sections of the flow path of the gas injection passage and the cross section of the air intake passage is the smallest of cross sections of the flow path of the air intake passage.

In another embodiment, a dryer includes a gas pipe for supplying gas; a valve to which the gas pipe is connected; a nozzle provided in the valve; a gas injection passage which is provided in the nozzle and through which the gas is injected; an air intake passage provided in the nozzle so as to be communicated with the gas injection passage; and a fastening part provided in the nozzle to mount the nozzle in the valve, wherein a diameter of the gas injection passage is smaller than a diameter of the air intake passage.

Preferably, the nozzle includes a nozzle for Liquefied Petroleum Gas (LPG) and a nozzle for Liquefied Natural Gas (LNG) which are detachably mounted in the valve. The diameter of the gas injection passage of the LPG nozzle is smaller than the diameter of the gas injection passage of the LNG nozzle. The diameter of the air intake passage of the LPG nozzle is smaller than the diameter of the air intake passage of the LNG nozzle.

Preferably, the diameter of the gas injection passage is the smallest of diameters of the flow path of the gas injection passage and the diameter of the air intake passage is the smallest of diameters of the flow path of the air intake passage.

According to the dryer having a gas heater of the present invention, since the structure of the nozzle for injecting the gas is improved and thus incomplete combustion is prevented, it is possible to reduce foreign substances produced upon the incomplete combustion an d save the amount of the gas taken to drive the dryer.

Also, according to the dryer having a gas heater of the present invention, since the gas heater is provided instead of an electric heater, it is possible to shorten the time for heating the heater.

Also, according to the dryer having a gas heater of the present invention, since various kinds of gas can be used as a fuel and it is possible to achieve a caloric value required for the dry by simply controlling the gas injection passage and the air intake passage, it is possible to reduce the time and cost taken to manufacture the dryer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a structural view showing a flow path of a conventional dryer.

FIG. 2 is a partially broken perspective view of the conventional dryer.

FIG. 3 is a structural view illustrating a dryer having a gas heater in accordance with an embodiment of the present invention.

FIG. 4 is an exploded perspective view illustrating a gas heater of the dryer in accordance with an embodiment of the present invention.

FIG. 5 is a perspective view illustrating a nozzle of the gas heater of the dryer in accordance with an embodiment of the present invention.

FIG. 6 is a longitudinal sectional view illustrating the nozzle of the gas heater of the dryer in accordance with an embodiment of the present invention.

FIG. 7 is a perspective view illustrating a flame holder of the gas heater of the dryer in accordance with an embodiment of the present invention.

FIG. 8 is a plan view illustrating an intake flow path of the dryer having a gas heater in accordance with an embodiment of the present invention.

FIG. 9 is a side sectional view illustrating a circulation flow path of the dryer having a gas heater in accordance with an embodiment of the present invention.

FIG. 10 is a plan view illustrating an exhaust flow path of the dryer having a gas heater in accordance with an embodiment of the present invention.

FIG. 11 is a graph showing content of carbon monoxide in exhaust gas of the dryer having a nozzle and a flame holder for LPG.

FIG. 12 is a graph showing content of carbon monoxide in exhaust gas of the dryer having a nozzle and a flame holder for LNG.

DESCRIPTION OF SPECIFIC EMBODIMENTS

Hereinafter, an exemplary embodiment of the present invention will be described with reference to accompanying drawings. For convenience of description, a dryer having a gas heater will be described by way of example. It should be noted that the drawings are not to precise scale and may be exaggerated in thickness of lines or size of components for the purpose of convenience and clarity only. Furthermore, terms used herein are defined in consideration of functions in the present invention and can be changed according to the custom or intention of users or operators. Thus, definition of such terms should be determined according to overall disclosures set forth herein.

FIG. 3 is a structural view illustrating a dryer having a gas heater in accordance with an embodiment of the present invention; FIG. 4 is an exploded perspective view illustrating a gas heater of the dryer in accordance with an embodiment of the present invention; FIG. 5 is a perspective view illustrating a nozzle of the gas heater of the dryer in accordance with an embodiment of the present invention; FIG. 6 is a longitudinal sectional view illustrating the nozzle of the gas heater of the dryer in accordance with an embodiment of the present invention; and FIG. 7 is a perspective view illustrating a flame holder of the gas heater of the dryer in accordance with an embodiment of the present invention.

Referring to FIGS. 3 to 7, a dryer having a gas heater in accordance with an embodiment of the present invention includes a cabinet 50 which is provided with an opening and discharge port 54, a drum 60 in which laundries to be dried is accommodated, a lifter 60 a which is mounted on an inner wall of the drum 60 to rotate the laundries to be dried, an intake duct 70 which guides air to the inside of the drum 60, a gas heater 100 installed in the intake duct 70, an exhaust fan 82 (refer to FIG. 10) which is provided between the drum 60 and the discharge port 54, an exhaust duct 80 which is provided between the exhaust fan 82 and the discharge port 54 and a driving motor 90 (refer to FIG. 10) which is connected with a rotation shaft of the exhaust fan 82.

When power is applied to the driving motor 90, the exhaust fan 82 is rotated to circulate air and the air flowed in the inside of the cabinet 50 is heated while passing the gas heater 100 and supplied to the inside of the drum 60 along the intake duct 70 to dry or sterilize the laundries to be dried. After that, the air is flowed along the exhaust duct 80 and exhausted to an outside through the discharge port 54 of the cabinet 50.

The drum 60 is formed in a cylindrical shape with opened front and rear portions. The front portion of the drum 60 corresponds to the opening of the cabinet 50 and the rear portion is rotatably mounted to a support panel 62 which is formed with a through hole part 62 a. The intake duct 70 is installed in the through hole part 62 a. Also, a front panel 64 is installed between the front end portion of the drum 60 and the opening of the cabinet 50 and is formed with an exhaust hole 64 a at a lower end portion thereof. A connection duct 84 extended toward the exhaust fan 82 is installed in the exhaust hole 64 a, and a housing (not shown) for rotatably housing the exhaust fan 82 therein is installed between the connection duct 84 and the exhaust duct 80.

The intake duct 70 is extended from the gas heater 100 to the through hole part 62 a. Therefore, the air flowed in form the inside of the cabinet 50 is heated while passing through the heater 100 and moved to the upper side of the cabinet 50 along the intake duct 70 to be flowed into the drum 60. At this time, a contact area between the hot air and the laundries to be dried is increased as the drum connected with the driving motor 90 by a belt (not shown).

The heater 100 includes a gas pipe 130 for supplying the gas to the inside of the cabinet 50, a valve 150 to which the gas pipe 130 is connected, a nozzle 140 provided in the valve 150, a mixing pipe 120 placed corresponding to the nozzle 140 to mix the gas and the air, an ignition plug 170 placed mounted in an outside of the mixing pipe 120 to generate sparks, a guide duct 110 placed at the outside of the mixing pipe 120 to guide the heated air, a bracket 160 which is provided on an inner wall of the cabinet 50 and on which the gas pipe 130, the mixing pipe 120 and the guide duct 110 are mounted and a flame holder 180 placed between the mixing pipe 120 and the guide duct 110 to prevent that a flame produced by the ignition plug 170 becomes larger than a predetermined size.

When the valve 150 is opened and the gas is supplied to the mixing pipe 120 along the gas pipe 130, the gas is mixed with the air inside the cabinet 50 to be injected to the outside of the mixing pipe 120 and the flame is then produced by the sparks generated in the ignition plug 170. Size and production position of the flame are controlled by the flame holder 180, so that the flame is placed inside the guide duct 110. The air flowed in along the guide duct 110 is changed to a hot wind with a high temperature while passing through the flame and then injected to the laundries to be dried.

The mixing pipe 120 is formed with a mixing part 124 at one side thereof to allow the air inside the cabinet to be flowed therein. Since the mixing part 124 includes an opening which is larger diameter than that of the nozzle 140, the gas injected from the nozzle 140 and air flowed in are mixed with each other in the mixing part 124. The mixing part 124 is formed in such a manner that an end of the mixing part 120 is extended and has a hollow cylindrical shape with an opening formed at the end thereof corresponding to the nozzle 140.

The nozzle 140 is communicated with the gas pipe 130 and detachably mounted on the valve 150. The nozzle 140 includes a gas injection passage 142 along which the gas is injected, air intake passages 144 communicated with the gas injection passage 142 to allow the air to be flowed into the gas injection passage 142 and fastening part 146 for mounting the nozzle 140 to the valve 150. When the valve 150 is opened and the gas is supplied to the mixing pipe 120 along the gas pipe 130, the gas is supplied to the mixing pipe 120 through the gas injection passage 142. At this time, the air is flowed in the gas injection passage 142 and the gas and the air are thus mixed with each other.

A cross section a of the gas injection passage 142 is formed smaller than a cross section b of the air intake passage 144. The cross section a of the gas injection passage 142 refers to the smallest of cross sections of the flow path of the gas injection passage 142 and the cross section b of the air intake passage 144 refers to the smallest of cross sections of the flow path of the air intake passage 144.

In the present embodiment, the cross sections of the gas injection passage 142 and the air intake passage 144 are described to have substantially a circular shape by way of an example. That is to say, in the present embodiment, a diameter a of the gas injection passage 142 is formed smaller than a diameter b of the air intake passage 144. Also, a length c of the fastening part 146 is formed greater than the diameter b of the air intake passage 144. Herein, The diameter a of the gas injection passage 142 refers to the smallest of diameters of the flow path of the gas injection passage 142 and flow velocity of the gas is increased while passing the section with such small diameter.

From the result of measuring shape, color and an amount of carbon monoxide (CO) due incomplete combustion caused by the nozzles 140 having various structures while controlling the diameter a of the gas injection passage 142, the diameter b of the air intake passage 144 and the length c of the fastening part 146, it could be appreciated that the incomplete combustion is prevented when the nozzle 140 has the shape as above described and the flame produced by the combustion of the gas is close to a blue flame.

The nozzle 140 includes a nozzle 140 a for a first gas and a nozzle 140 b for a second gas. In the present embodiment, the nozzle 140 a for a first gas is a nozzle 140 a for Liquefied Petroleum Gas (LPG) and nozzle 140 b for a second gas is a nozzle 140 b for Liquefied Natural Gas (LNG). Referring to FIG. 6, the diameter a of the gas injection passage 142 a of the LPG nozzle 140 a is formed smaller than the diameter a′ of the gas injection passage 142 b of the LNG nozzle 140 b and the diameter b of the air intake passage 144 a of the LPG nozzle 140 a is formed smaller than the diameter b′ of the air intake passage 144 b of the LNG nozzle 140 b. The reason that the diameters of the LNG nozzle 140 b is greater than the diameters of the LPG nozzle 140 a is because a more amount of the LNG should be supplied compared to the LPG as a caloric value of the LNG is smaller than a caloric value of the LPG.

Table 1 below shows the result of inspecting generation of a red flame while supplying gas with the LPG nozzle 140 a so that the caloric value is 5,040 Kcal/h, and Table 2 shows the result of measuring the generation of the red flame and noise (dB) while varying the diameter b of the air intake passage 144 a in a state that the diameter a of the gas injection passage 142 a is fixed to 1.4 mm and the length c of the fastening part 146 a is fixed to 4.0 mm.

TABLE 1 Generation of red flame a b C 1^(st) 2^(nd) 3^(rd) 1.0 1.8~2.2 3.8~4.2 ◯ ◯ ◯ 1.2 1.8~2.2 3.8~4.2 X X X 1.4 1.8~2.2 3.8~4.2 X X X 1.6 1.8~2.2 3.8~4.2 X X X

TABLE 2 Generation of red flame a b c 1^(st) 2^(nd) 3^(rd) Noise (dB) 1.4 1.0 4.0 ◯ ◯ ◯ 35 1.5 ◯ ◯ X 35 2.0 X X X 37 2.5 X X X 40 3.0 X X X 43

As can be appreciated from Tables 1 and 2, in the case of the NPG nozzle 140 a, it is preferable that the diameter a of the gas injection passage 142 a is 1.2 to 1.6 mm, the diameter b of the air intake passage 144 a is 1.8 to 2.2 mm and the length c of the fastening part 146 a is 3.8 to 4.2 mm. When considering the noise, the optimum flame is produced preferably when the diameter a of the gas injection passage 142 a is 1.4 mm, the diameter b of the air intake passage 144 a is 2.0 mm and the length c of the fastening part 146 a is 4 mm.

Table 3 below shows the result of inspecting generation of the red flame while supplying gas with the LNG nozzle 140 b so that the caloric value is 5,040 Kcal/h, and Table 4 shows the result of measuring the generation of the red flame and noise (dB) while varying the diameter b′ of the air intake passage 144 b in a state that the diameter a′ of the gas injection passage 142 b is fixed to 2.0 mm and the length c′ of the fastening part 146 b is fixed to 3.0 mm.

TABLE 3 Generation of red flame a{grave over ( )} b{grave over ( )} c{grave over ( )} 1^(st) 2^(nd) 3^(rd) 1.6 2.8~3.2 3.8~4.2 ◯ ◯ ◯ 1.8 2.8~3.2 3.8~4.2 X X X 2.0 2.8~3.2 3.8~4.2 X X X 2.2 2.8~3.2 3.8~4.2 X X X

TABLE 4 Generation of red flame a{grave over ( )} b{grave over ( )} c{grave over ( )} 1^(st) 2^(nd) 3^(rd) Noise (dB) 2.0 2.0 4.0 ◯ ◯ ◯ 37 2.5 ◯ X X 38 3.0 X X X 40 3.5 X X X 45 4.0 X X X 50

As can be appreciated from Tables 3 and 4, in the case of the LNG nozzle 140 b, it is preferable that the diameter a′ of the gas injection passage 142 b is 1.8 to 2.2 mm, the diameter b′ of the air intake passage 144 b is 2.8 to 3.2 mm and the length c′ of the fastening part 146 b is 3.8 to 4.2 mm. When considering the noise, the optimum flame is produced preferably when the diameter a′ of the gas injection passage 142 b is 2.0 mm, the diameter b′ of the air intake passage 144 b is 3.0 mm and the length c′ of the fastening part 146 b is 4 mm.

In a case of manufacturing the LPG nozzle 140 a and the LNG nozzle 140 b so as to produce the optimum flame, the LPG nozzle 140 a supplies the gas of about 3.5 L/min and the LNG nozzle 14 b supplies the gas of about 8.0 L/min, thereby capable of generating the caloric value of about 5,040 Kcal/h.

The nozzle 140 has a shape of a polygonal prism and each face forming the polygon is formed with the air intake passage 144. When the air intake passage 144 is formed on the face of the polygon, processing of the air intake passage 144 can be facilitated and a shape error generated upon the processing as compared with a nozzle of which air intake passage is formed on edge of the polygon. Particularly, it is preferable that the sectional shape of the nozzle 140 is formed in a hexagon and the air intake passage 144 is formed on each face forming the hexagon. By forming the nozzle in the structure as described above, the optimum flame can be produced. This structural characteristic is also determined, as the structure capable of producing the optimum flame, from the results of a plurality of experiments performed by varying the sectional shape of the nozzle 140 and varying the number of the air intake passage 144.

The flame holder 180 is installed in the mixing pipe 120 so as to be disposed between the mixing pipe 120 and the guide duct 110. A mixture of the air and the gas forms a vortex by the flame holder 180 and the mixture is thus burned in the vicinity of flame holder 180. The flame holder 180 includes a body 182 formed with a through hole part 182 a through which the mixture supplied through the mixing pipe 120 is injected, and a plurality of supports 184 which are extended from the body 182 to be connected with an end portion of the mixing pipe 120. Herein, the body 182 is formed in a ring shape, in which the through hole part 182 a is formed in the middle of the ring and a plurality of the wings 186 is formed at the periphery of the ring. The wings 186 are provided in plural in a radial direction on the periphery of the body 182, and a pair of the supports 184 is extended from the wings which oppose to each other. Herein, the wing 186 is bended towards the mixing pipe 120 with a predetermined angle.

The mixture injected to the outside of the mixing pipe 120 is ignited by the sparks generated by the ignition plug 170. Since the mixture are spread by the body 182 and the wings 186 of the flame holder 180, the flame produced is not formed long along the guide duct 110 but is gathered in the vicinity of the flame holder 180. Since the flame is gathered in the middle of the inside of the guide duct 110 by the aforementioned operation, it is possible to prevent the mixing pipe 120 or the intake duct 70 is deformed or damaged by the flame. Herein, the support 184 includes a mounting part 184 a fastened to the mixing pipe 120 and a fixing part 184 b which connects the mounting part 184 a and the body 182, and a width of the fixing part 184 b is narrower than a width of the mounting part 184 a. Therefore, the contact area between the mixture and the fixing part 184 b is reduced and it is thus possible to prevent that the mixture injected from the mixing pipe 120 is flowed back after collided with the support 184. By the aforementioned operation, it is possible to prevent the backflow of the flame in which the mixture injected from the mixing pipe 120 is burned while being flowed back to the mixing pipe 120 after collided with the support 184. Also, since the fixing part 184 b of the support 184 has smaller thickness than the mounting part 184 a, it is possible to effectively prevent the backflow of the flame.

The through hole part 182 a has a large diameter d as compared with a distance e between the wing 186 and the mixing pipe 120 (refer to FIGS. 7 and 8). Specifically, the diameter d of the through hole part 182 a is 9.8 to 10.2 and the distance e between the wing 186 and the mixing pipe 120 is 8.8 to 9.2. When the diameter d of the through hole part 182 a and the distance e between the wing 186 and the mixing pipe 120 were as aforementioned, the flame had such a shape that the flame is clustered around the body 182 and a blue flame was also formed. This structure prevents that the flame is formed long inside the guide duct 110 and the red flame is produced, thereby capable of preventing the incomplete combustion of the gas. The diameter d of the through hole part 182 a and the distance e between the wing 186 and the mixing pipe 120 as described above are the values determined by experiments performed plural times.

Hereinafter, operation of the dryer having a gas heater in accordance with an embodiment of the present invention will be described.

FIG. 8 is a plan view illustrating an intake flow path of the dryer having a gas heater in accordance with an embodiment of the present invention; FIG. 9 is a side sectional view illustrating a circulation flow path of the dryer having a gas heater in accordance with an embodiment of the present invention; and FIG. 10 is a plan view illustrating an exhaust flow path of the dryer having a gas heater in accordance with an embodiment of the present invention.

Referring to FIGS. 5 to 7 and FIGS. 8 to 10, when a user manipulates an operation button (not shown), the power is applied to the driving motor 90 to rotate the exhaust fan 82 and the drum 60. By the driving of the exhaust fan 82, the air flowed in the inside of the cabinet 50 is moved to an upside of the cabinet 50 along the intake duct 70 vertically formed on a rear face of the cabinet 50. At this time, as the valve 150 of the heater 100 is opened and the gas is supplied along the gas pipe 130, the gas passed through the valve 150 passes through the nozzle 140 to be injected to the inside of the mixing pipe 120 and then primarily mixed with the air flowed in through the nozzle 140 and secondarily mixed with the air flowed in through the space between the mixing pipe 120 and the nozzle 140. Herein, gas/air ratio of the mixture is determined by the shape of the nozzle 140, or the structural characteristics of the nozzle 140 such as the diameter a of the gas injection passage 142, the diameter b of the air intake passage 144 and the length c of the fastening part 146, and the incomplete combustion can be prevented when these structural parts has the dimensions as described above. Of course, though the distance between the nozzle 140 and the mixing pipe 120 is a factor that determines the gas/air ratio of the mixture, in the present invention, the distance between the nozzle 140 and the mixing pipe 120 is considered to be the same as that conventionally used and thus not be described specifically.

When the mixture of the air and gas is injected through the mixing pipe 120 and the flame is produced by the ignition plug 170. Since the injected mixture collides with the flame to form a vortex, the flame is laterally spread in the vicinity of the flame holder 180. At this time, since the fixing part 184 b of the support 184 has thinner thickness than the thickness of the mounting part 184 a, the support 184 of the flame holder 180 can prevent the mixture moving toward the support 184 is collided with the support 184 and the body 182 and then flowed back. Since the flame is spread in the vicinity of the body 182 of the flame holder 180 and is prevented from being flowed back to the mixing pipe 120 along the support 184, it is possible to prevent the incomplete combustion. Also, since this flame is gathered in a middle of the guide duct 110 by the flame holder 180, it is possible to prevent the deformation or damage of the mixing pipe 120 and the intake duct 70. This is because it is possible to prevent that the flame is formed long inside the guide duct 110 as the mixture is spread by the body 182 and the wing 186 of the flame holder 180 and it is thus possible that the flame is produced at a position close to the intake duct 70.

The air flowed in the inside of the intake duct 70 along the guide duct 110 is heated to dry air with a high temperature while being brought into contact with the flame. After that, the air flowed in the inside of the drum 60 through the through hole part 62 a is swirled and brought into contact with the laundries to be dried to perform the dry operation.

The front panel 64 placed between an inner wall of the cabinet 50 and the opening of the drum 60 is formed with an exhaust hole 64 a. The air is exhausted to the outside of the drum 60 through the exhaust hole 64 a, flowed to the housing 86 of the exhaust fan 82 through the connection duct 84 communicated with the exhaust hole 64 a, then move from the housing 86 along the exhaust duct 80 and finally exhausted to the outside of the cabinet 50 through the discharge port 54.

FIG. 11 is a graph showing content of carbon monoxide in exhaust gas of the dryer having a nozzle and a flame holder for LPG and FIG. 12 is a graph showing content of carbon monoxide in exhaust gas of the dryer having a nozzle and a flame holder for LNG.

Referring to FIGS. 5 to 7, 11 and 12, the dimensions of the nozzle 140 and the flame holder 180 as described above are determined as the optimum dimensions in an experiment, in which shape and color of the flame and carbon content in the exhaust gas according to structural variation of the nozzle 140 and the flame holder 180, performed on August, 2007 by New Energy Laboratory in department of mechanical engineering of Incheon University according to a request of present assignee.

In addition, the nozzle 140 and the flame holder 180 manufactured with the above described dimensions were installed in the dryer to be subject to a safety inspection. Particularly, with respect to the content of carbon monoxide in the exhaust gas, the content of the carbon monoxide was detected by less than 6 ppm in a dryer with the LPG nozzle 140 a and by less than 7 ppm in a dryer with the LNG nozzle 140 b. Therefore, it can be appreciated that the incomplete combustion is prevented.

Although the present invention has been described with reference to the embodiments shown in the drawings, it should be understood that these embodiments are provided for illustrative purpose and that various equivalent modifications and alterations will be apparent to those skilled in the art without departing from the scope and spirit of this invention. In addition, although the present invention has been described with reference to the dryer as specifically described herein, it should be noted that the dryer has been illustrated by way of example, and that the gas heater of the present invention may be applied to other product such as a washing machine, without being limited to the dryer in its application. Therefore, the scope and spirit of the invention is limited only by the claims set forth herein as follows. 

1. A dryer, comprising: a nozzle communicated with a gas pipe for supplying gas; a gas injection passage which is provided in the nozzle and through which the gas is injected; and an air intake passage provided in the nozzle so as to be communicated with the gas injection passage, wherein a cross section of the gas injection passage is smaller than a cross section of the air intake passage.
 2. The dryer of claim 1, wherein a diameter of the gas injection passage is smaller than a diameter of the air intake passage.
 3. The dryer of claim 2, further comprising a fastening part provided in the nozzle to mount the nozzle.
 4. The dryer of claim 3, wherein the length of the fastening part is greater than the diameter of the air intake passage.
 5. The dryer of claim 3, wherein the nozzle includes a nozzle for a first gas and a nozzle for a second gas.
 6. The dryer of claim 5, wherein the nozzle for a first gas includes a nozzle for Liquefied Petroleum Gas (LPG) and the nozzle for a second gas includes a nozzle for Liquefied Natural Gas (LNG) and the diameter of the gas injection passage of the LPG nozzle is smaller than the diameter of the gas injection passage of the LNG nozzle.
 7. The dryer of claim 6, wherein the diameter of the air intake passage of the LPG nozzle is smaller than the diameter of the air intake passage of the LNG nozzle.
 8. The dryer of claim 6, wherein, in the LPG nozzle, the diameter of the gas injection passage is 1.2 to 1.6 mm and the diameter of the air intake passage is 1.8 to 2.2 mm.
 9. The dryer of claim 8, wherein the length of the fastening part is 3.8 to 4.2 mm.
 10. The dryer of claim 6, wherein, in the LNG nozzle, the diameter of the gas injection passage is 1.8 to 2.2 mm and the diameter of the air intake passage is 2.8 to 3.2 mm.
 11. The dryer of claim 10, wherein the length of the fastening part is 3.8 to 4.2 mm.
 12. The dryer of claim 1, wherein the nozzle has a shape of a polygonal prism and the air intake passage is formed on a face which forms the polygon.
 13. The dryer of claim 1, wherein the cross section of the gas injection passage is the smallest of cross sections of the flow path of the gas injection passage and the cross section of the air intake passage is the smallest of cross sections of the flow path of the air intake passage.
 14. A dryer, comprising: a gas pipe for supplying gas; a valve to which the gas pipe is connected; a nozzle provided in the valve; a gas injection passage which is provided in the nozzle and through which the gas is injected; an air intake passage provided in the nozzle so as to be communicated with the gas injection passage; and a fastening part provided in the nozzle to mount the nozzle in the valve, wherein a diameter of the gas injection passage is smaller than a diameter of the air intake passage.
 15. The dryer of claim 14, wherein the nozzle includes a nozzle for Liquefied Petroleum Gas (LPG) and a nozzle for Liquefied Natural Gas (LNG) which are detachably mounted in the valve.
 16. The dryer of claim 15, wherein the diameter of the gas injection passage of the LPG nozzle is smaller than the diameter of the gas injection passage of the LNG nozzle.
 17. The dryer of claim 15, wherein the diameter of the air intake passage of the LPG nozzle is smaller than the diameter of the air intake passage of the LNG nozzle.
 18. The dryer of claim 14, wherein the diameter of the gas injection passage is the smallest of diameters of the flow path of the gas injection passage and the diameter of the air intake passage is the smallest of diameters of the flow path of the air intake passage. 